Humans are well-adapted to life on Earth. But when we move into space it's a different story. Low or zero gravity changes how the blood circulates, weakens the immune system, causes motion sickness, muscle loss and fatigue. Weightless can also trigger bone loss. VOA’s Rosanne Skirble reports on a laboratory experiment with tiny, almost microscopic worms designed to help us better understand the impact long-term space travel will have on future astronauts